1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and a method of forming a pattern of LCD device by printing.
2. Discussion of the Related Art
Typically, a liquid crystal display (LCD) device includes lower and upper substrates and a liquid crystal layer formed between the lower and upper substrates. The lower substrate typically includes a thin film transistor and a pixel electrode and the upper substrate may include a light-shielding layer, a color filter layer and a common electrode.
An LCD device is provided with various components patterned by repeated processes. Photolithography is used to pattern the plurality of components in the various shapes used in the LCD device. Photolithography uses a mask having a predetermined pattern and a light-irradiation device resulting in an increase in the cost of manufacturing LCD devices. In addition, photolithography includes exposure and development processes that complicate the manufacturing process and increase manufacturing time.
To overcome the problems associated with photolithography, new patterning methods, such as a printing method, have been developed.
In the printing method, a predetermined material is coated on a printing roll, and the printing roll coated with the predetermined material is then rolled on a substrate to transcribe predetermined pattern onto the substrate. Hereinafter, a related art printing method will be described with reference to the accompanying drawings.
FIGS. 1A to 1C schematically illustrate a related art printing method.
First, as shown in FIG. 1A, a pattern material 20 is applied to a printing roll 30 through a printing nozzle 10. A blanket 35 adheres to the outer surface of printing roll 30 and is coated with the applied pattern material 20. The blanket 35 should have properties of good adherence to the printing roll 30 and high resistance to deformation during the printing process. The blanket 35 is typically formed of a Si-based resin.
After coating the pattern material onto the printing roll, as shown in FIG. 1B, the printing roll 30 is rolled onto a printing plate 40 having a plurality of protruding patterns 46 and groove patterns 43. As a result, some 20a of the pattern material is transcribed or transferred onto the protruding patterns 46 of printing plate 40, leaving remaining pattern material 20b to form a predetermined pattern on the blanket 35 of the printing roll 30.
Referring to FIG. 1C, the printing roll 30 is rotated on a substrate 50 and the remaining pattern material 20b on printing roll 30 is transcribed on the substrate 50, thereby forming the desired pattern on the substrate 50.
Using the above described printing method allows omitting the exposure and development processes used in photolithography. Accordingly, the printing method has lower fabrication cost and uses simpler processes than do processes using photolithography, making the printing method suitable for use in the mass-production.
As the pattern formation of printing method is performed repeatedly, a solvent of pattern material 20 is absorbed into the blanket 35 adhering to the outer surface of printing roll 30. As a result of absorbing the solvent, the blanket 35 may swell deforming the shape of the blanket 35. The deformation of the blanket 35 may interfere with forming a precise pattern.
For example, as shown in FIG. 2A, if during the process of rolling the blanket 35 of printing roll 30 coated with the pattern material 20 on the printing plate 40 provided with the protruding patterns 46 and groove patterns 43, the blanket 35 has a swollen portion, the pattern material 20 may contact the printing plate 40 within the groove patterns 43 of the printing plate 40. As a result of the contact within the groove patterns 43 of the printing plate 40, as shown in FIG. 2B, some of the pattern material 20b is transferred onto the groove patterns 43 in addition to the pattern material 20a that is transcribed on the protruding patterns. Accordingly, pattern material 20c remaining on the blanket 35 of printing roll 30 does not include the pattern material formed in region “A” and the desired precise pattern on the printing roll 30 is not formed.